header.gif  

Historical Review
Process Capabilities
Process Advantages
Part Design
Design vs. Material
Size Capabilities
Nominal Walls
Depth of Draw Ratio
Stretch Ratio
Corner Radii
Draft Angles
Stiffening Details
Holes
Trim Lines
Undercuts
Tolerances
As Formed Tolerances
Machining Tolerances
Texturing
Decorating
Cost Considerations
The Thermo Pressure Forming Process
Attributes vs. Processes
 
Stretch Ratio  

The stretch ratio can be defined as the ratio of the surface area of the formed part to the net starting area of the original sheet. An average stretch ratio of 3 to 1 is considered to be maximum for Thermo Pressure Forming. An average stretch ratio of 2 (or less) to 1 would be preferred.